Cannot setup Nswag in my vb.net webapi project

Question

I have to set a WebApi project (in .NET Framework 4.6.1) written in VB.NET and i want to setup Nswag and Swagger for further implementation. I look for that guide: enter link description here and all of my C# webapi projects works well

I'm trying setup in VB.NET converting the code like that:

Public Module WebApiConfig
Public Sub Register(ByVal config As HttpConfiguration)
    ' Servizi e configurazione dell'API Web

    ' Route dell'API Web
    config.MapHttpAttributeRoutes()

    config.Routes.MapHttpRoute(
        name:="DefaultApi",
        routeTemplate:="api/{controller}/{action}/{id}",
        defaults:=New With {.id = RouteParameter.Optional}
    )

    config.MessageHandlers.Add(New TokenValidationHandler())

    Dim appXmlType = config.Formatters.XmlFormatter.SupportedMediaTypes.FirstOrDefault(Function(t) t.MediaType = "application/xml")
    config.Formatters.XmlFormatter.SupportedMediaTypes.Remove(appXmlType)

    RouteTable.Routes.MapOwinPath("swagger", Function(app)
                                                 app.UseSwaggerUi3(GetType(WebApiApplication).Assembly, Function(settings)
                                                                                                            settings.MiddlewareBasePath = "/swagger"
                                                                                                            settings.GeneratorSettings.DefaultUrlTemplate = "api/{controller}/{action}/{id}"
                                                                                                            settings.GeneratorSettings.OperationProcessors.Add(New OperationSecurityScopeProcessor("JWT Token"))
                                                                                                            settings.GeneratorSettings.DocumentProcessors.Add(New SecurityDefinitionAppender("JWT Token",
                                                                                                                                            New NSwag.OpenApiSecurityScheme With
                                                                                                                                            {
                                                                                                                                            .Type = NSwag.OpenApiSecuritySchemeType.ApiKey,
                                                                                                                                            .Name = "Authorization",
                                                                                                                                            .Description = "Copy 'Bearer ' + valid JWT token into field",
                                                                                                                                            .[In] = NSwag.OpenApiSecurityApiKeyLocation.Header
                                                                                                                                            }))
                                                                                                        End Function)
                                             End Function)
End Sub

End Module

But when i run the project pop up that error:

No conversion available between VB$AnonymousDelegate_0`2[System.Object,System.Object] and System.Func`2[System.Collections.Generic.IDictionary`2[System.String,System.Object],System.Threading.Tasks.Task]. Parameter name: signature

setting the error on line 28 of my code that correspond for RouteTable.Routes.MapOwinPath("swagger", Function(app)

Any Suggestion?

Answer 1

I found out that VB.NET lamba functions must have specified the type they return like so:

 RouteTable.Routes.MapOwinPath("swagger", Function(app) As Owin.IAppBuilder
                                                 Return app.UseSwaggerUi3(GetType(WebApiApplication).Assembly, Function(settings) As SwaggerUi3Settings(Of NSwag.Generation.WebApi.WebApiOpenApiDocumentGeneratorSettings)
                                                                                                                   settings.MiddlewareBasePath = "/swagger"
                                                                                                                   settings.GeneratorSettings.DefaultUrlTemplate = "api/{controller}/{action}/{id}"
                                                                                                                   settings.GeneratorSettings.OperationProcessors.Add(New OperationSecurityScopeProcessor("JWT Token"))
                                                                                                                   settings.GeneratorSettings.DocumentProcessors.Add(New SecurityDefinitionAppender("JWT Token",
                                                                                                                                            New NSwag.OpenApiSecurityScheme With
                                                                                                                                            {
                                                                                                                                            .Type = NSwag.OpenApiSecuritySchemeType.ApiKey,
                                                                                                                                            .Name = "Authorization",
                                                                                                                                            .Description = "Copy 'Bearer ' + valid JWT token into field",
                                                                                                                                            .[In] = NSwag.OpenApiSecurityApiKeyLocation.Header
                                                                                                                                            }))

                                                                                                                   Return settings
                                                                                                               End Function)
                                             End Function)

notice that I add As Owin.IAppBuilder and As SwaggerUi3Settings(Of NSwag.Generation.WebApi.WebApiOpenApiDocumentGeneratorSettings)